Method for applying elements to surfaces of constructed objects used for road traffic

ABSTRACT

An environmentally sound method for applying or fixing elements ( 2 ) to constructed objects used for road traffic. The element ( 2 ), which is at least partially made of a material that can be liquefied by mechanical energy, is positioned on the surface, is pressed against the surface, and is simultaneously subjected to a local mechanical stimulation to liquefy the liquefiable material, and the element ( 2 ) binds with the surface upon re-solidifying. A mobile device ( 1 ) for applying elements ( 2 ) of this type, includes device that can travel via rolls or rollers ( 4, 5 ) and that is provided with at least one oscillating unit ( 10 ) including a sonotrode ( 6 ), a converter ( 7 ) and of an amplifier ( 8 ), and with a generator ( 9 ). The element ( 2 ) may be a marking or signaling element to be applied to roads or tunnel walls.

BACKGROUND OF THE INVENTION

The invention relates to a method according to the preamble of the firstpatent claim. The method serves for attaching or fastening elements onsurfaces of construction objects in the road traffic field, for examplefor attaching marking elements or signalling elements on roads orsquares, in garages or multi-storey car parks or on house or tunnelwalls, that is to say on surfaces which in particular consist of asphaltor concrete. The invention also relates to a device for carrying out themethod and to an element being able to be attached with the method,according in each case to the preambles of the respective patent claims.

Known methods for attaching for example markings onto road surfaces areessentially based on two different processes, namely a process ofthermally creating a material fit and a process of chemically creating amaterial fit.

According to a method of the first group, thermoplastic strips and theasphalt surface lying below this are melted down with a gas flame, sothat the molten materials bond to one another after cooling. Thedisadvantage of this method lies in the fact that on the one hand a verylarge volume of the road surface needs to be heated and on the otherhand the method is very time consuming due to the long heating-up andcooling-down phases. Furthermore the energy requirement is very high andthe melting process is difficult to control and therefore little suitedfor automation. Handling of naked flames and gas containers furthermoreentails safety risks and is therefore connected with an increasedhandling effort.

According to a method of the second group, solvent-containing coatingsof paint are sprayed onto the designated surface. For this method thesurface needs to be thoroughly cleaned prior to being coated, and thenthe marking geometries need to be covered or suitable stencils need tobe positioned. Sprayed markings are deposited however only in a verysuperficial manner and, due to wear and abrasion, have mostly only ashort serviceable life. Furthermore, during application or duringabrasion of the coats of paint, solvent, colour particles and otherpartly noxious substances get into the environment. It is further knownto attach premanufactured markings to surfaces using adhesives, suchattaching having the same disadvantages as discussed above.

It is the object of the invention to provide a method for permanent ortemporary attachment of elements to surfaces of construction objects inthe road traffic field, i.e. to surfaces which in particular consist ofasphalt or concrete.

BRIEF SUMMARY OF THE INVENTION

According to the invention the elements, for example marking orsignalling elements consist at least partly of a material which isliquefiable by way of mechanical excitation, e.g. of a thermoplasticmaterial. This means that the element consists of a material with atleast one liquefiable (e.g. thermoplastic) component, or at least aregion of the element to be directed towards the surface on which it isto be attached consists of such a material. The element is positioned onthe surface on which it is to be attached and then it is at leastlocally pressed against the surface and mechanically excited in a mannersuch that the liquefiable material is liquefied at least locally andtemporarily, and after re-solidification forms a bond between thesurface and the element. The surface onto which the element is pressedmay also be partly liquefied by the mechanical excitation. Themechanical excitation is usually based on excitation by a sonotrode(piezoelectric excitation for higher frequencies, magnetostrictiveexcitation for lower frequencies). The excitation is preferably based onmechanical oscillation at a frequency lying in the range of ultrasound,and as the case may be also at lower frequencies. The frequencies areselected depending on the field of application. By way of varying thefrequency the extent to which the liquefiable material and, as the casemay be, surrounding regions (background) are liquefied or heated may bedetermined. The amplitude, the frequency and the excitation durationinfluence the extent of liquefaction and heating. A further essentialaspect is the way in which the mechanical oscillation is coupled intothe element to be attached or into the element region which is to beliquefied respectively. For such coupling, the element may e.g. be madeto be part of the oscillating body. By partially liquefying andsubsequent re-solidification, advantageously combined with simultaneouspressing, a bond is produced between the element and the surface onwhich the element is to be attached.

According to the invention the energy used for liquefying theliquefiable material is introduced in a locally and temporallycontrolled manner. By way of this locally and temporally controlledapplication of energy, adjacent regions are not unnecessarily heated,which fact creates various advantages. On the one hand the bond can becreated using considerably less energy. All the same, the resultingbond, due to the way and manner in which it is created, is extremelylasting and has a high loading capacity. On the other hand the bond canbe created in considerably less time since considerably less time isrequired for introducing the required energy. The method according tothe invention is also environmentally friendly since no furtherauxiliary agents such as adhesives, solvents or other bonding agentscomprising noxious substances are used.

The strength of the bond is influenced by the intensity of themechanical energy (impulse, frequency) and/or the excitation duration.According to the field of application it is thus possible to createbonds which are very lasting, or which may be easily detached again. Byway of longer excitation duration or by way of a more intense excitationas a result of a higher frequency or amplitude, a stronger bond isachieved, because e.g. more material is liquefied.

The method according to the invention is suitable for the most variedapplications in the field of road traffic, as for example in roadconstruction, realisation of signs or markings, sealing of gaps, etc.Amongst other things the method is suitable for attaching marking stripsor marking images which for example are supplied in the form of suitablypunched films and are for example attached to the surfaces of streets ortunnel walls, e.g. stripes marking middle or edge of roads, arrows orlettering.

The method according to the invention is also suitable for applyingsignalling elements which are to project functionally beyond the surfaceon which they are attached. Such signalling elements are for example tobe understood as elements which are to be attached in the region of thecentre line or an edge line of a road and which elements when drivenacross notify the driver by vibrating his vehicle. When required, suchelements may be designed reflecting so that they may be better seenparticularly in poor light conditions. In particular on motorways theseelements may be designed such that they have properties which aredifferent with respect to direction. One example of such an elementreflects white in the travel direction and red in the oppositedirection. By way of this a person driving on the wrong side of the roadis made aware of his mistake. Other designs are also possible.

The method according to the invention is particularly suitable forfastening elements which are fabric-like or are based on a filmmaterial. These in particular are middle lines and side lines on roads,markings for pedestrian crossings, stop lines, direction indicators(arrows) etc. The elements may be quasi endless (continuous lines) orlimited. The film material of such elements advantageously comprises atwo-dimensional or net-like substrate film which for example is providedwith a coating being liquefiable by way of mechanical excitation. Thismechanically liquefiable coating is provided on the one side of thesubstrate to be directed towards the road surface and it is even orcomprises projecting elements which serve as energy directors, i.e. forconcentrating the exciting mechanical energy in a manner such that alocally intensified melting-down occurs.

The side of the elements to be directed towards the surface on which theelement is to be attached may be coated with a liquefiable material onlyin regions. Instead of the coating, three-dimensional regions of theliquefiable material may be provided, for example pins, rings or othershapes, which are for example uniformly distributed over the surface ofthe element to be attached to the road surface or other surface. Theposition of such three-dimensional shapes is suitably marked on theopposite side from which the mechanical oscillation is coupled in, sothat the mechanical energy may be selectively introduced in the correctlocations.

A further field of application of the method according to the inventionis the fastening of reinforcements to surfaces of construction objectsin the field of road traffic. From the state of the art there are knownmethods with which bridges, in particular bridges of concrete arerestored by attaching strips of high-tensile, stiff fibres (e.g. carbonfibres) on the lower bridge side, i.e. in the region in which thestructure is loaded in tension. Such strips relieve the bridge structureor allow it to be more loaded. According to the state of the art suchstrips are attached by way of adhesive which is a cost-intensive andthus expensive method. It is furthermore not very suitable due toenvironmental aspects. On attaching the strips, the fibres must beprestressed so that the structure is relieved in an effective mannerfrom the very beginning. However prestressing is not linear but must begreatest along the middle and lowest along at edges of the bridge. Usingthe method according to the invention, it becomes possible to processthe above described reinforcement strips very simply and alsoinexpensively in a continuous process. The reinforcement strips arepressed onto the surface of the construction object to be reinforced,they are prestressed depending on location and are then connected to thesurface by way of mechanical excitation and pressure. Since theconnection is created in a very short time, non-linear prestressingensuring optimal results is easily possible.

The bonds created with the method according to the invention may bepermanent or may be only temporary. Temporary bonds are to be understoodas bonds which are only to be present for a forseeable time duration.Such bonds make sense, in particular in the field of building siteswhere it is necessary to divert the traffic for a certain time. Suchbonds are created in a very simple manner and they can be easilydetached later. In the field of building sites it makes particular senseto attach temporary markings which comprise a film, for example in theform of an endless tape as a base structure and which comprise a coatingbeing able to be bonded to the road surface by way of mechanicalexcitation. Using a suitable device, endless or limited signallingelements may be attached very simply in a continuous process. In orderto detach the elements the same device may be used in a reverse way andmanner (new liquefaction, detachment and then removal). The bonds may beformed such that the strips can be detached without special tools.Pretreatment of the surface on which the elements are to be attached,e.g. for drying such surfaces, may be effected by preheating the surfaceby e.g. using a hot roller which is more suitable than a gas flame. Incertain cases such pretreatment (drying, priming) may not be required.The method may be applied for various element thicknesses and elementgeometries. Other than in the known melt-on processes, the materialthickness can be optimized. The time required for the mechanicalexcitation may be reduced and the bonding improved by way of preheating.Bonds created according to the invention are characterised by their goodadhesion on the most varied of porous surfaces. They display a goodresistance to specific influences such as weather, wear, etc.

Since the method has no influence on the geometry of the element to befastened, customer-specific geometries can be realized, as well ascustomer-specific surface structures and colourings. A surface structuremay be embossed during attaching by the tool used for attaching or by asubsequent tool. This surface structure may assume additional functions,e.g. creating noise when in contact with a rotating tyre, so that thedriver is made aware that he is crossing the marking.

The advantages of the method according to the invention may besummarized as follows:

-   -   Carrying out the method is extremely simple and gives high        performance at low operating and maintenance expense;    -   Good bonding between the attached element and the surface on        which it is attached is achieved due to liquefaction of a part        of the material during the fastening procedure;    -   Improved bonding with respect to known methods using an open gas        flame is achieved, due to the fact that no incineration occurs        and no soot particles contaminate the bonding surfaces;    -   Very short process times (time for mechanical excitation and for        resolidification or cooling) are possible;    -   The device for attaching the elements does not need to carry        liquid, volatile or inflammable substances, which fact        considerably increases the working safety;    -   The method is environmentally friendly since above all no        volatile substances or auxiliary agents are applied.

In combination with the following Figures the method according to theinvention and some exemplary embodiments of devices for carrying out themethod according to the invention, and of elements being attachable onconstruction objects using the method are described in more detail.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a first embodiment of a device forattaching marking strips;

FIG. 2 is a perspective view of a second embodiment of a device forattaching marking strips, the device comprising a link chain;

FIG. 3 is a perspective view of a third embodiment of a device forattaching marking strips, the device comprising a sonotrode roller;

FIG. 4 is a cross-sectional view a section through a sonotrode roller;and

FIGS. 5 to 8 show further examples of elements which are attachable tosurfaces of construction objects of road traffic using the methodaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1, in a greatly simplified manner, shows the essential elements ofa first embodiment of a fastening device for attaching an element 2, forexample a marking element (marking strip) on the surface of a road, forexample of asphalt or concrete. The element 2 to be attached isstrip-like and is separated from a tape, wherein the tape is rolled on asupply reel 3. The element 2 for example comprises a substrate materialwhich is coated on at least one side. It is for example a strip ofplastic or metal film being coated with a material which can be melteddown using mechanical excitation. This meltable or liquefiable materialis for example a thermoplastic polymer material (e.g. polypropylene).The element 2 may also consist completely of the meltable material.

While the fastening device 1 is moved in the working direction tape forthe element 2 is rolled from the supply reel 3 and by way of a firstroller 4 is pressed onto the surface (e.g. road surface) on which theelement 2 is to adhere. The working direction is shown by an arrow X.Behind the first roller 4 three sonotrodes 6 are provided being activelyconnected to a converter (sound transducer) 7 and to a mechanicalamplifier 8. The converter 7 which serves for converting electrical intomechanical oscillation is driven via a generator 9. The converterusually comprises piezoelements converting electrical oscillation withtypical frequencies above 20 kHz into suitable mechanical oscillation.The working range of the converter is selected to suit the application.Normal frequencies lie in the range between 2 kHz and 400 kHz.

The amplifier 8 functions as a mechanical amplifier due to itsconfiguration. It transforms oscillation, concentrates this oscillationand transmits it to the sonotrode 6. The sonotrode 6 together with theamplifier 8 and the converter 7 forms an oscillating unit 10. Theelements of the oscillating unit 10 are optimised to the field ofapplication or to a frequency and preferably oscillate in resonance. Theoscillating unit 10 excites into oscillation the element 2 and whereappropriate the material of the surface to which the element 2 is to beattached. Through internal and external friction caused by theexcitation, the element is melted, at least locally, and as the case maybe, the surface material too. Due to high shear effects a high degree ofplastification is achieved. The element 2 is advantageously pressed(roller 5) against the surface on which it is to be attached duringliquefaction and afterwards, so that after resolidification the elementand the surface are connected to one another. The shown fastening device1 comprises three oscillating units 10. These may be activatedindividually. It is of course to be understood that a device may have adifferent number of oscillating units.

Behind the three oscillating units 10 there is a second roller 5 whichpresses the element 2 against the surface during the cooling. The firstand the second rollers 4, 5 serve preferably for setting the distancebetween the sonotrodes 6 and the element 2. The fastening device 1serves for fastening the element 2 in a continuous or in a discontinuousprocess.

A cutting device 11 is arranged behind the second roller 5. This deviceserves for cutting off the element 2 if the marking strip to bedeposited is not continuous as is shown. The discontinuous case isindicated schematically in FIG. 1 by a first element 2 of a marking tapebeing shown behind the fastening device. In front of the first roller 4there is a detaching device 12 which serves for detaching elements 2from a surface on which they have previously been attached, followingre-liquefaction of the element by the oscillating units.

The type of the oscillation and the manner of its coupling into theelement 2 to be fastened is determined by the shape of the sonotrode 6and the other elements of the oscillating unit. Preferred are elongateor cylindrical shapes which extend over the whole width of the element 2and taper downwards, i.e. towards the element 2 to be treated.

FIG. 2 shows a further embodiment of a fastening device 1 for attachingan element 2 to a surface. The fastening device 1 comprises two lowerrollers 13 and two upper rollers 14 which serve for guiding acirculating link chain 15. The link chain 15 on its outer surface has anembossing structure 16 which serves for embossing a surface structure 17into the element 2. A sonotrode 6 is arranged between the two lowerrollers 13 and serves for the indirect excitation of the element 2 viathe link chain 15. The element 2 being processed is arranged between thelink chain 15 and the surface on which it is to be attached. Thetape-like material for the element 2 is stored on a supply reel 3 and ispulled from this during the process. A cutting device 11 serves forcutting off an element 2 of material on the supply reel 3. This cuttingdevice may be arranged in front of or behind the link chain 15.Different surface structures may be embossed into the element 2 by wayof using link chains 15 with different embossing structures 16.

For driving the fastening device 1, preferably electrical or hydraulicmotors (not shown in detail) are used. The fastening device 1 isdesigned preferably self-travelling or may be used as a part of anothermachine. For processing differently shaped elements 2 it has acorresponding configuration.

FIG. 3 shows a further embodiment of a fastening device 1 for attachingelements 2 on a surface. The fastening device 1 comprises an oscillatingunit 10 with a rotating sonotrode 6. The sonotrode 6 is designed as asonotrode roller which is preferably excited by a converter 7 tooscillate in a radial direction. The oscillation is transmitted to theelement 2 and has the effect that this element is plastified locally.Rollers 4, 5 are arranged in front of and behind the sonotrode roller 6in the working direction (x-direction). These rollers serve for pressingthe element 2 onto and into the surface of the background. Ifapplicable, rollers 4, 5 are also guiding and support rollers. A cuttingand detaching device 11, 12 are arranged in front of and behind therollers. These devices comprise a blade each and when activated cut offthe element 2 or detach it from the surface on which it is fastened.

FIG. 4 shows a schematic section along the axis of the sonotrode roller6 according to FIG. 3. As may be recognised, the sonotrode roller 6consists of a plurality of stacked disks 18 being connected to oneanother centrically via thin locations 13. The oscillation of theconverter 7 is preferably introduced perpendicularly to the axis A ofthe sonotrode roller.

The invention may be summarized as follows: an environmentally friendlyand safe method for attaching or fastening elements on surfaces ofconstruction objects in the field of road traffic which methodcomprises: positioning the element to be attached on the surface onwhich it is to be attached and liquefying the element by localmechanical excitation during an excitation time so that the element onits side facing the surface and where appropriate also the surface ontowhich the element is pressed is locally melted in a manner such thatafter cooling the element is fastened on the surface. A travellingdevice for attaching a marking strip for example onto the surface of aroad comprises a means being capable of travelling on rolls or rollers4, 5, and further comprising at least one oscillating unit 10 consistingof sonotrode 6, converter 7 and amplifier 8 and a generator 9. Themarking strips attached onto the surface of the road apart from theircolouring may have a profiling which produces acoustic or variousoptical signals, such as e.g. white reflection in the one direction andred reflection in the other direction.

FIGS. 5 to 8 show further elements 2 which may be attached to surfacesof construction objects according with the method according to theinvention. These elements are discrete elements which may not be woundoff from a supply reel. They may however be positioned in a per se knownmanner at predefined time intervals below the oscillation tool of afastening device moving at a constant speed for example along a road, sothat they are deposited onto the road surface at constant distances toone another. The elements may also be attached individually with a handapparatus known from ultrasonic welding or with a similar apparatus.

FIG. 5 shows a flat element 2 which is shown to be rectangular, butwhich however may have any shape. The element along the edge comprisesnubs 20 arranged on the one element side which is to be directed towardsthe surface on which the element is to be attached. At least these nubsconsist of the liquefiable material, where appropriate the whole edgeregion or the nub-side of the edge region consist of this material. Forthe attachment process, the element according to FIG. 5 is positionedand is pressed against the surface and simultaneously excited (e.g. withan excited sonotrode) at least in its edge region (indicated by arrows).

The element 2 according to FIG. 6 is disk-like and for example comprisesa reflector in the middle of its side facing outwards. On its oppositeside which is to be directed towards the surface on which the element isto be attached, the element 2 comprises a fastening ring 2. In theregion of this ring 21 the element is excited from the outside, as thisis illustrated by the arrows, and is pressed against the surface, forexample with a corresponding tubular sonotrode. The fastening ring 21may also be formed by a row of pins or nubs arranged along the edge ofthe element 2. At least the fastening ring 21 or the pins or nubsserving the same purpose, or where appropriate the whole element 2consist of a material which is liquefiable by way of mechanicaloscillation.

FIG. 7 shows a disk-like element similar to the element of FIG. 6. Anelectronic module 25 with an aerial 16, as is used for traffic directingor controlling systems, is arranged on the side facing the surface onwhich the element is to be attached. By fastening the element with thefastening ring 21 a hermetically closed space is created for theelectronic module. The element 2 according to FIG. 7 may of course alsohave a shape other than a disk-like shape.

FIG. 8 shows a further element with an integrated electronic module 25comprising an aerial 26. Module and aerial are positioned between twoelement parts 2.1 and 2.2, wherein these two element parts may forexample be connected to one another on fastening of the whole element.The element part 2.2 directed towards the fastening side of the elementconsists at least partly of the liquefiable material. The two elementparts 2.1 and 2.2 may also be connected to one another e.g. by anadhesive prior to attachment of the element on the surface. It is alsopossible to integrate the electronic module into the element duringmanufacturing of the element 2 by e.g. moulding.

1. A method for attaching elements (2) to surfaces of constructionobjects in the field of road traffic, wherein the element (2) consistsat least partly of a material that is liquefiable by being pressedagainst a surface and by mechanical excitation and wherein the elementis positioned on the surface, pressed against the surface andmechanically oscillated at least locally via an oscillation unitcomprising a sonotrode (6), a converter (7) and a generator (9), suchthat the liquefiable material at least in a region facing said surfaceis at least partly liquefied, and after re-solidification, forms a bondbetween the element and the surface.
 2. The method according to claim 1,wherein the mechanical oscillation is generated piezoelectrically or bymagnetostriction.
 3. The method according to claim 1, wherein themechanical oscillation has a frequency which lies in a range ofultrasound.
 4. The method according to claim 1, wherein the element (2)is part of a continuous or interrupted line marking, that it is unreeledfrom a tape being wound on a supply reel and that it is continuously orintermittently positioned on the surfaces pressed against the surface,and excited.
 5. The method according to claim 1, wherein the element (2)is disk-shaped and is excited and pressed with the help of a tubularsonotrode.
 6. The method according to claim 1, wherein the element (2)is a marking or signaling element, an element for gap sealing, or areinforcement element suitable for superficial arrangement.
 7. A device(1) for attaching elements (2) on surfaces of construction objects inthe field of road traffic, comprising means to travel on rollers orrolls (4, 5), the means further comprising at least one oscillating unit(10), the oscillating unit comprising a generator (9), a sonotrode (6),and a converter (7).
 8. The device according to claim 7, wherein thetraveling means with the at least one oscillating unit (10) furthercomprises a supply reel (3) with a tape-like material for the element(2).
 9. The device according to claim 8, wherein the traveling meanswith the at least one oscillating unit (10) further comprises a cuttingdevice (11) for cutting off elements (2) from the tape-like material.10. The device according to claim 7, wherein, for detaching the element(2) from the surface, the traveling means further comprises a detachingdevice (12).
 11. An element (2) for being attached with the methodaccording to claim 1 on surfaces of construction objects of roadtraffic, said element comprising at least in a surface region, which isto be directed towards said surface, a material that is liquefiable bybeing pressed against the surface and by being excited throughmechanical oscillation.
 12. The element according to claim 11, furthercomprising energy directors in said surface region.
 13. The elementaccording to claim claim 11, further comprising pins, nubs or fasteningrings consisting of the liquefiable material in said surface region. 14.The element according to claim 11, wherein said element is film-like.15. The element according to claim 14, wherein said element isstrip-like or tape-like.
 16. The element according to claim 11, furthercomprising integrated further function elements.